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Why Your Car Won’t Start In Cold Weather (+ Fixes & Tips)

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Cold weather can effectively ruin your car’s system, leaving you with an engine that refuses to crank up. 

But, do you know why your car won’t start in cold weather?
And what can you do to restart your car?

In this article, we’ll go over eight reasons why a car won’t start in the cold weather and then show you what to do about it. We’ll also drop some expert tips to prepare your car for the winter and answer a few cold car FAQs

This Article Contains:

(Click on a link to jump to the specific section) 

Let’s get started. 

8 Reasons Why Your Car Won’t Start In Cold Weather

Your car may refuse to start in the cold for so many reasons. 

Sometimes it could be a dead battery or a failed ignition coil, and sometimes a faulty coolant temp sensor is to be blamed. Needless to say, it’s always best to have a professional look into the problem

To give you a heads up, here are some common problems behind a no-start in cold temperature:

1. Cold Car Battery

A cold battery is the most probable reason why your car fails to start in the cold. If you get a whining noise at ignition, a dead battery may be preventing the starter motor from turning over. 

But why? 
When a car is kept in an unheated garage, the cold weather slows down the chemical reaction inside the car battery. And cold car batteries fail to produce the same amount of power as warm batteries.

The engine oil also becomes thicker in cold weather. As a result, it requires twice as much power from the battery under normal conditions.

2. Car Fluid Thickening 

A low temperature can cause the engine oil, transmission fluid, antifreeze, etc., to thicken. It requires more effort to pump them through the engine block. 

This extra effort to pump the oil also strains your battery, preventing it from performing at optimum levels. As a result, your car won’t start.

If you drive a diesel engine, bear in mind that diesel fuel also becomes gel-like in extreme cold and can take longer to pump and power your car engine during ignition.

3. Moisture In Your Fuel Line

Getting fuel to the engine requires more than just filling the gas tank. 

The fuel system includes a fuel injector, a fuel pump, a fuel pump relay, and several fuel lines that transfer fixed amounts of fuel from one point to another.

In some cases, moisture in a fuel line can freeze and result in lower fuel pressure or blockage. 

But how does the moisture reach the fuel line? 
The gas or fuel in the fuel tank needs to vaporize first before it can burn. 

When the level of the gas in your fuel tank drops, it gives more room for condensation. This condensation moves from the gas tank to the fuel line. When the temperature drops, it freezes and prevents the gas from reaching your car’s engine. 

4. Using The Wrong Oil

Thick oil like 10W-30 can make it difficult for your car engine to crank in low temperature conditions. To counter this, most new vehicles today use a thinner oil like 5W-20. You’ll likely find your current General Motors, Ford, or Honda vehicle specifying thinner oil viscosities like this.

If you are unsure which engine oil to use, check with your vehicle’s user manual or visit your nearest auto parts store, where someone can guide you. 

5. Your Car Is Fitted With A Carburetor

If you drive a car manufactured more than 30 years ago, it’d likely have a carburetor fitted inside. The carburetor mixes fuel from the gas tank with air to make it combustible in the engine block. 

The small nozzles on carburetors are highly susceptible to dropping temperatures and can easily get clogged with ice, preventing the engine from powering up.  

In this case, here’s a possible solution:

  1. Place one foot on the clutch.
  2. Now push the accelerator pedal with the other foot when you turn on the ignition switch. This’ll pre-inject some additional fuel in the engine block and start your car. 

Note: If you own a modern car, it won’t have a carburetor. However, most new vehicles today use a fuel injector to eliminate this hassle. 

6. Faulty Alternator

If you have a new battery and it keeps going flat, it could be the car’s alternator. A faulty alternator doesn’t charge properly, and will leave you with a weak battery. 

You can find an alternator replacement at an auto parts store. However, since the alternator is connected to the engine and your car’s battery, we recommend contacting a mechanic to come over or calling a tow truck or roadside assistance to get the alternator fixed or replaced. 

7. Bad Starter Motor

More often than not, a car won’t start due to a bad starter motor. When there’s a faulty starter relay, you’ll hear a clicking sound on turning the ignition switch, followed by the engine refusing to turn over. 

Even jumpstarting your car won’t work with a bad starter. In such a situation, it’s best to head to an auto parts store or call a mechanic to diagnose and replace the starter motor

8. Aging Spark Plug

The spark plug in your car ignites the air-fuel mixture in the fuel system that helps your engine to produce power. 

If your spark plug is aging or if its wires are worn out, it may fail to do its job. 
Ideally, you should get your plug inspected or replaced every 30,000 to 90,000 miles. 

Now that you know what may be giving your engine a cold start, let’s see how you can address these issues and restart your cold car. 

How To Restart A Cold Car

Here are some options you could try to crank up your engine when your car suffers a cold start.

A. Turn Everything Off

The headlights, car heater, and other electronics use the car battery to power up. If you live in extremely cold weather, it’s best to turn them off before you try to start the car. 

This’ll help direct the battery’s charge to power up the engine. Once the engine starts, let it run for a few minutes before switching on the heater or any other electronic accessory. 

B. Check Battery Cables and Terminals

Corrosion around the battery cable or a battery terminal can lead to weak battery voltage, causing transient current flow that prevents your car from starting.

Locate the battery and check the negative and positive terminal as well as the battery cable for signs of corrosion. 

Disconnect the battery terminal and give the crusty substance a solid cleaning with a mixture of baking soda and water. Even if the battery cable is corrosion-free, tighten the clamps before turning on the ignition switch. 

C. Fill Up Your Engine Oil

If your car is low on engine oil, it can lead to friction between parts and damage vital engine components. 

Low engine oil also puts additional strain on your car battery as the engine takes more time to crank up. And if the battery is already cold, it’ll fail to power your car. To prevent this, use a dipstick to check your engine oil level and, if needed, fill it up. 

D. Dip The Clutch During Ignition

Dipping the clutch as you turn on the ignition disengages the gearbox. This way, the battery only needs to power the starter motor. 

This reduces the load on the battery and improves the chances of your engine turning over even if you have a cold car. However, this cold start trick only works with manual transmission vehicles. 

E. Jumpstart Your Car

In case you have a dead battery, you can try to jumpstart your engine with the help of a running car that’ll work as a charger. 

To jumpstart a vehicle, you’ll need a jumper cable to connect your car’s battery to a running car. If you own a regular car, go for a jumper cable with a gauge of 6. 

Turn on the running car and let it run for a few minutes before turning on your vehicle. Avoid turning on the heater or other electronic accessories, as it will lead to an unnecessary drain of the battery. For details on jumpstarting, check out this Dead Car Battery guide.

F. Call For Assistance 

Unless you’re well-versed at auto repair, you shouldn’t attempt fixing your car issues yourself. 

Call for a tow truck or roadside assistance if your car fails to start. 

Alternately, you can get hold of a mobile mechanic that’ll come to your home when you can’t start your car on a cold morning.

In that case, your answer is RepairSmith!

RepairSmith is a highly convenient and affordable mobile auto repair and maintenance solution.

With RepairSmith:

For an accurate cost estimate of car starting repairs, fill out this online form.

Knowing how to troubleshoot is one thing, but it’d be better to avoid having a cold car in the first place, right?

How To Prepare Your Car For Winters? (Care Tips)

Here are a couple of tips for car owners to prepare their car for the cold weather: 

A. Winterize The Car 

It’s advisable to get your car battery and engine oil checked before the winter sets in. 

Further, your car’s tire pressure can drop by 1 PSI (pounds per square inch) for every 10 degrees drop in temperature. It happens because the air inside the tire condenses, taking up less space when it’s cold. So you should get your tire pressure checked as well. 

You can also get winter tires from an auto shop to brave the icy roads and prep your car for winter driving. 

B. Warm-up Your Engine

Turn on the ignition and leave your vehicle idle for 30 seconds at least. This gives your engine enough time to warm up and avoids putting unnecessary strain on the engine block. 

C. Install An Engine Block Heater 

If the temperature in your area falls below -15°C, getting a safe engine block heater from an auto shop is a good idea. 

A block heater warms up the coolant and the engine, allowing the engine oil to flow freely through the engine block. 

If your car uses diesel fuel, you may need a block heater even before the temperature drops that low. 

Besides using an engine block heater, diesel fuel cars also have glow plugs that work as a heater to warm up the incoming fuel and air for efficient fuel combustion. Glow plugs have indicators that show when the car is warm enough to start.

If you don’t have a block heater or glow plugs, you can park your car in a heated garage or buy an electric engine warming blanket to cover the battery.

D. Care For Your Battery 

Before winters start, get a thorough battery health check from a professional car repair service like RepairSmith

If your battery is more than three years old and you only use your car for short trips, charge your battery once every week. And if it still fails to hold a charge, it’s best to get a new battery for a safe winter driving experience. 

You can install a battery with the highest cold cranking amps (CCA) rating. Cold Cranking Amps or CCA is a rating used in the battery industry to define a battery’s ability to start an engine in cold temperatures. 

E. Use Starter Fluid 

Since starter fluid is more combustible than your car fuel, it ignites easily from the spark plug and generates more force for your engine to turn over. 

Car owners can remove the air filter and spray a very small amount of starter fluid into the air intake. Then, replace the air filter and turn on the ignition. 

Note: We strongly recommend calling a professional mechanic to look into the problem before you try this method, or you can end up causing severe damage to your engine block. 

F. Keep A Check On The Coolant

The job of the coolant is to prevent the water in your car’s cooling system from freezing in cold conditions. Besides that, it also provides lubrication to the moving parts of the engine. If the coolant level is lower than the full line, you must top it up to prepare your car for the cold.

G. Replace Your Windshield Wipers

Replace your windshield wipers as they can develop cracks due to freezing temperatures. 

Also, remember to lift up your windshield wipers at night to prevent them from freezing onto the windshield and breaking on a cold morning. 

H. Renew Car Insurance

Repairing car damage caused by extreme cold can be expensive. So don’t forget to renew your car insurance annually to mitigate such financial losses from the winter. 

Now that we have all the causes, solutions, and care tips sorted, let’s go over some cold car-related FAQs.

4 Car Won’t Start In Cold FAQs

Here are some common questions that car owners have when their car won’t start in cold conditions:

1. How Do Cold Temperatures Affect My Car?

Cold temperature and other adverse weather conditions can affect your vehicle in many ways: 

2. Can Extreme Cold Kill My Car Battery?

A fully charged new battery will only freeze at -57°C. However, if you have a dead battery, it can freeze at around 0°C. Even if you thaw the battery, the charge will be weak and won’t last long. 

3. Can Petrol Or Motor Oil Freeze?

The engine oil doesn’t freeze but becomes highly viscous in the cold. 

It’s advisable to use engine oil with a lower W rating, like 5W-20. The freezing point of petrol is below -50°C, so you can rest assured that the gas in your fuel tank won’t freeze any time soon unless you hit arctic temperatures. 

You can also switch to a synthetic oil that performs better in the cold than conventional oils. Synthetic oil flows better for easier starts and protects your car against wear. 

4. Should I Park My Car Inside A Garage In Winter? 

Car batteries often lose power in a colder temperature, taking longer time than usual to start the engine. So it’s best to keep your car in warmer, covered parking spaces. 

Moreover, parking indoors spares you the trouble of scraping ice off the windows or brushing snow off the top before leaving the house.

In the absence of a closed parking space, you can unhook the terminals of your car’s battery and bring it inside for the night to keep the battery warm.

Closing Thoughts

There are a few things you can try out when your car won’t start in the freezing temperatures.

But as always, it’s best to avoid this situation from happening in the first place. Use the tips we mentioned to prepare your vehicle for the winter to avoid struggling every morning, trying to crank up your engine. 

And if you’re wondering who you should contact when your car won’t start in cold weather, give RepairSmith a try! Our expert technicians will get your cold vehicle up and running right in your driveway!